Phase III, multi-centre, randomised, double blind, Placebo-controlled study for treatment of juvenile ankylosing spondylitis (AS) with Adalimumab by Thon A, Tzaribacev N, Kuester R, Kuemmerle-Deschner K, Foeldvari I, Huppertz HI, Fitter S, Horneff G, Borte M, Ganser G, Trauzeddel R, Minden K